GOG 



PHYSIOLOGY. 



These have been termed the perivascular sheaths of His. Between 

 them and the vessels exists a lymph-space : one of the origins of the 

 lymphatics. 



White-substance Formation. The white matter is formed by the 

 bundles of white fibers covered by a lamellar investment of iieuroglia. 

 These bundles are separated from one another by tracts of connective 

 tissue detached from the pia mater. 



Axis-cylinders are also found, which come from the gray matter. 

 Blood-vessels anastomose and run in a course parallel with the nerve- 

 fibers. This circulatory network likewise has a perivascular sheath as 

 has that in the gray substance. 



Chemical Properties of Nervous Substance. The following table 

 of Landois gives the percentage of the various components of both 

 gray and white matters : 



In 100 parts of ash, Breed found potash, 32; soda, 11 ; magnesia, 

 2; lime, 0.7; NaCl, 5; iron phosphate, 1.3; fixed phosphoric acid, 

 39 ; sulphuric acid, 0.1 ; and silicic acid, 0.4. 



Composition of Nerve-tissue, According to Halliburton, (a) 

 Proteids. Over 50 per cent, in gray matter. They are : 



1. Neuro-globulin (alpha), coagulates at 47 C. 



2. A imcleo-proteid which, like other proteicls. causes ex* 



tensive iniravascular coagulation. 



3. A neuro-globulin (beta). 

 (&) Nuclein from nuclei of cells. 



(c) Neuro-keratin, from neuroglia. 



(d) Phosphorized fats. 



1. Lecithin; when decomposed it gives rise to glycero- 

 phosphoric acid, stearic acid, and choline. 



